The present invention relates to modifiers for iron and methods of using same in ferrous metallurgy, more specifically in foundry practice.
Commonly known in the art is the use of modifiers to be added into liquid iron to minimize the formation of cementite on the surface of castings.
Presence of the layer of white iron on the casting surface hinders its machining and impairs quality of cast iron, since this layer has low physico-mechanical properties.
Accordingly, iron castings are subjected to annealing in thermal furnaces with the view to increase physico-mechanical properties of the superficial layer of cast iron and improve machinability thereof.
Annealing of iron castings makes possible to increase mechanical properties of the superficial layer and improve machinability of castings, however, on the account of impaired characteristics of the base metal and higher production costs of castings.
British Pat. No. 1,223,694 discloses an additive comprising a mixture of ferrosilicium and rare-earth metals taken in the following proportions, percent by weight:
______________________________________ ferrosilicium 90 to 100 rate-earth metals 0 to 10. ______________________________________
This additive, however, does not make it possible to obtain iron castings with a wall thickness of below 2 mm, using sand-loam molds.
Lack of an iron modifier which would made it possible to manufacture iron castings without the formation of cementite on the surface of cast iron does not provide for a reduced power consumption in annealing furnaces, or reduced costs of auxiliary equipment and operation personnel.